JPS6150243B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hysteresis level measuring circuit that measures the hysteresis level of a circuit under test having hysteresis characteristics.

An example of a conventional circuit of this type is shown in FIG. 1 and will be explained. In the figure, 1 is a program power source which is a source of voltage generated by the program, and 2 is a program value of the program power source 1, which is +α, - depending on the output state.
3 is a reference setting circuit that sets the initial value for the program power source 1, 4 is a memory circuit that stores the value of the program power source 1, and 5 is a memory circuit that calculates several values of the memory circuit 4 (mainly by subtraction). ) arithmetic circuit, 6
is a GO/NG judgment circuit that judges the value of the arithmetic circuit 5;
7 is a circuit (device) to be measured having hysteresis characteristics.

Next, the operation of this measuring circuit will be explained.
First, initial value data is sent from the reference setting circuit 3 to the program power supply 1. Then, the program power supply 1 converts this data into an analog voltage,
Supplied to device 7. Next, if there is no change in the output of the device 7, an increase command of +α is sent from the addition/subtraction command circuit 2 to the program power supply 1. As a result, the program power supply 1 supplies the analog voltage increased by +α to the device 7. This is then repeated until there is a change in the output of the device 7.

Next, when a change in the output occurs, the output value of the program power supply 1 at that time is stored in the storage circuit 4. (MEMO1) Here, this storage command is generated from the addition/subtraction command circuit 2. Further, the command sent from the addition/subtraction command circuit 2 to the program power source 1 is changed from +α to -α. Then, the above-described process with +α changed to -α is repeated until there is a change in the output of the device 7.

When a change in the output occurs, the output voltage value of the program power supply 1 at that time is stored again in the memory circuit 4.
(MEMO2). Then, in the arithmetic circuit 5
Subtracts MEMO1 - MEMO2 and outputs the hysteresis value. Then, when determining the hysteresis value, the GO/NG determination circuit 6 performs the determination. FIG. 2 is an explanatory diagram showing an example of the input/output pattern, and ΔV is a hysteresis value.

However, a circuit with such a configuration has the drawback that the auxiliary circuits tend to be complicated, and failures and malfunctions are likely to occur. Further, it has the disadvantage that it takes time to see the output after supplying the input, and it is susceptible to noise. Furthermore, if the value of +α given by the addition/subtraction command circuit is large, the error will be large, and if it is made small, it will take unnecessary time.

In view of the above points, the present invention has been made to eliminate such drawbacks, and its purpose is to provide a hysteresis level measuring circuit that can simplify the circuit and stabilize the measurement.

In order to achieve such an objective, the present invention
Controlled by the output of the blow-out type constant current source, the suction type constant current source, and the circuit under test, the output of the blow-out type constant current source is selected first, and when the output of the circuit under test changes in the increasing direction, the suction type constant current an output switching circuit that selects a source, selects the output of the blow-out type constant current source again when the output of the circuit under test changes in a decreasing direction, and repeats these selection operations; It has a capacitor that is charged by a constant current from the source and discharged by a constant current flowing to the sink type constant current source, and a time constant circuit that applies the terminal voltage of this capacitor to the input of the circuit under test, and a hysteresis level of the circuit under test. Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 3 is a block diagram showing an embodiment of a hysteresis level measuring circuit according to the present invention. In FIG. 3, the same symbols as in FIG. 1 indicate corresponding parts, 8 is a buffer power supply that supplies voltage to the device 7, 9 is a time constant circuit including a capacitor C and a resistor R for generating a triangular wave, 10 1 is an output switching circuit that connects the suction type constant current source 11 or the blowout type constant current source 12 to the time constant circuit 9 depending on the output state;
3 is a frequency counter that counts the frequency of the output out determined by the hysteresis level from the device 7, and this counted value becomes the hysteresis value.

FIG. 4 is an explanatory diagram showing an example of an input/output pattern for explaining the operation of FIG. 3, where AA indicates an example of input,
BB shows an input example. CC indicates the output for AA, and DD indicates the output for BB.

Next, the operation of the embodiment shown in FIG. 3 will be explained with reference to FIG. 4.

In FIG. 3, the output switching circuit 10 first selects the output of the blowout type constant current source 12, and in order to supply the constant current from now on to the time constant circuit 9, the output switching circuit 10 selects the output of the constant current source 12. Accordingly, the capacitor C is charged, the terminal voltage of the capacitor C gradually rises, and this terminal voltage is applied to the input IN of the device 7 via the buffer power supply 8 using a DC amplifier or the like.
given to.

When the voltage at the input IN increases as shown in Figure 4 (A) and the output CC changes in the increasing direction in (B), the output switching circuit 10 selects the sink type constant current source 11 in response to this, so this is the case. The constant current starts discharging the capacitor C and the charges, and the terminal voltage of this gradually decreases, and the input IN voltage also decreases as shown in C.

When the input IN voltage drops and reaches D, the output CC
changes in the decreasing direction, so the output switching circuit 10 selects the blow-out type constant current source 12 again in response to this, and as a result, charging of the capacitor C is restarted, and the terminal voltage of the capacitor C is prevented from rising. The input IN voltage also rises as shown in E.

Therefore, since the output switching circuit 10 repeats the above operation according to the change in the output OUT, the input
The voltage at IN becomes a triangular wave, and correspondingly, the change in the output OUT becomes a pulse. Therefore, the change frequency of the output OUT is measured by the frequency counter 13, and the period 1/ is calculated from the frequency determined by this. If determined, the hysteresis value ΔV will be approximately 1/2, as is clear from FIG.

Note that this calculation may be performed by the GO/NG judgment circuit 6, and depending on the characteristics of the device 7, the input BB
The same applies if the output is as shown in DD. That is, to be exact, ΔV=1/2α1/. Here, α is a value determined by the time constant circuit 9,
is the frequency.

In this way, the hysteresis level of the object to be measured having hysteresis characteristics can be measured.

As is clear from the above explanation, according to the present invention, since one measurement becomes multiple measurements, the accuracy is high and it is resistant to noise etc. Furthermore, the circuit configuration is simplified, so it is economical. It is effective for

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of a conventional hysteresis level measuring circuit, FIG. 2 is an explanatory diagram showing an example of an input/output pattern to explain the operation of FIG. 1, and FIG.
FIG. 4 is a block diagram showing an embodiment of the hysteresis level measuring circuit according to the present invention, and FIG. 4 is an explanatory diagram showing an example of an input/output pattern for explaining the operation of FIG. 3. 7...Device, 8...Buffer power supply, 9...
Time constant circuit, 10...Output switching circuit, 11...Suction type constant current source, 12...Blowout type constant current source, 13...
...Frequency counter.

Claims (1)

[Claims] 1. In a circuit for measuring the hysteresis level of a circuit under test having hysteresis characteristics, a blow-out type constant current source, a suction type constant current source, and an output of the blow-out type constant current source controlled by the output of the circuit under test are first set. When the output of the circuit under test changes in the increasing direction, the suction type constant current source is selected, and when the output of the circuit under test changes in the decreasing direction, the output of the blowing type constant current source is changed again. an output switching circuit that selects and repeats these selection operations; and a capacitor that is charged by a constant current from the blow-out type constant current power source via the output switching circuit and discharged by a constant current passed to the suction type constant current source. A hysteresis level measurement characterized by comprising: a time constant circuit that applies the terminal voltage of the capacitor to the input of the circuit under test; and a frequency counter that measures an output change frequency determined by the hysteresis level of the circuit under test. circuit.